1. Technical Field
The present invention relates to a liquid supplying apparatus, a liquid ejecting apparatus, and a liquid supplying method.
2. Related Art
A liquid ejecting apparatus that ejects liquid (e.g., ink) onto a recording target medium (e.g., paper) to form a predetermined image (including characters, a figure, or the like) on the recording target medium is known in the art. A liquid supplying needle that is in communication with a liquid ejecting head is inserted into a liquid container, which contains liquid that is to be ejected. The liquid is supplied from the liquid container to the liquid ejecting head through the liquid supplying needle. The liquid ejecting apparatus ejects the liquid from the liquid ejecting head. To avoid the aged deterioration of an image, it is known that some liquid ejecting apparatuses of related art use liquid having excellent environment resistance (i.e., weatherability). Liquid that includes pigment as its solute is a popular example of such liquid having excellent environment resistance.
As is commonly known, since liquid that includes pigment is water-based dispersion liquid, the distribution of pigment particles in a solvent is generally poor. Because of poor pigment distribution, the pigment particles tend to precipitate in the liquid contained in a liquid container in the direction of gravitation force. For this reason, the density of liquid that is supplied to a liquid-ejecting-head side through a liquid supplying needle could lack uniformity depending on the distribution density of pigment particles. Consequently, an image formed with the use of such liquid will be poor due to shading irregularities or the like, which will be caused by a difference in the liquid density.
To provide a solution to the above problem that arises when liquid that includes pigment is used, the following technique is disclosed in, for example, JP-A-2002-200766. A liquid container such as an ink pack, which contains liquid, has a cylindrical shape. The liquid container is periodically rotated around the axis of its cylindrical body by an angle of rotation of 180 degrees. By this means, the liquid including pigment is stirred in the liquid container. The technique disclosed in JP-A-2002-200766 reduces the difference in the liquid density in this way.
In many cases, liquid containers are mass-produced at the same time to increase production efficiency. Therefore, liquid containers are sometimes stored for a long period in a warehouse or the like. During the storage of a liquid container for a long period, there occurs a large concentration gradient, that is, a large gradient of density, of pigment particles from the bottom of the liquid container, toward which the pigment particles of the liquid are gravitated, to the top of the liquid container.
In the technique disclosed in JP-A-2002-200766, a liquid container is periodically rotated around the axis of its cylindrical body by an angle of rotation of 180 degrees after the attachment of the liquid container to a liquid ejecting apparatus and the insertion of a liquid supplying needle into the liquid container. That is, even when the liquid container is in a needle-inserted state after the attachment thereof to the liquid ejecting apparatus, the liquid contained in the liquid container has not been stirred yet before the programmed periodic rotation thereof starts.
For this reason, when attaching a liquid container stored for a long period to a liquid ejecting apparatus, a user must stir the liquid contained in the liquid container by shaking it or by any other means before the attachment of the liquid container to the liquid ejecting apparatus. If the user forgets to shake the liquid container beforehand, there is a possibility that an image that is formed as a result of ejection of the liquid supplied from the liquid container immediately after the attachment may be poor due to shading irregularities or the like.